Heat reversible gel and method for preparing same

ABSTRACT

A COMPOSITION FOR PRODUCING A SYNERGISTIC INCREASE IN THE VISCOSITY OF AN AQUEOUS SYSTEM AND FOR FORMING A HEAT REVERSIBLE, AQUEOUS SYSTEM AND FOR FORMING A HEAT PHILIC COLLOID AND LOCUST BEAN GUM, WHEREIN THE WEIGHT RATIO OF SAID XANTHOMONAS HYDROPHILIC COLLOID TO SAID LOCUST BEAN GUM RANGES FROM ABOUT 95:5 TO ABOUT 5:95. THE VICOUS AQUEOUS MEDIUM IS MADE BY ADDING THE XANTHOMONAS HYDROPHILIC COLLOID AND LOCUSTBEAN GUM TO WATER. THE HEAT REVERSIBLE, AQUEOUS GEL CAN BE MADE BY ADDING A MIXTURE OF XANTHOMONAS HYDROPHILIC COLLOID AND LOCUST BEAN GUM TO HOT WATER, AND THEREAFTER COOLING. THE HEAT REVERSIBLE, AQUEOUS GEL CAN ALSO BE MADE BY ADDING TO WATER A MIXTURE OF XANTHOMONAS HYDROPHILIC COLLOID AND LOCUST BEAN GUM, AND MIXING UNDER HIGH SHEAR AGITATION.

United States Patent 3,557,016 HEAT REVERSIBLE GEL AND METHOD FORPREPARING SAME Harry R. Schuppner, Jr., El Cajon, Calif., assiguor toKelco Company, San Diego, Calif, a corporation of Delaware No Drawing.Filed Oct. 22, 1965, Ser. No. 502,446 Int. Cl. A231 1/04; B013 13/00;C09g 1/02 US. Cl. 252-316 21 Claims ABSTRACT OF THE DISCLOSURE Acomposition for producing a synergistic increase in the viscosity of anaqueous system and for forming a heat reversible, aqueous gel comprisingXanthomonas hydrophilic colloid and locust bean gum, 'wherein the weightratio of said Xanthomonas hydrophilic colloid to said 10- cust bean gumranges from about 95 :5 to about 5 :95. The viscous aqueous medium ismade by adding the Xanthomonas hydrophilic colloid and locust bean gumto water. The heat reversible, aqueous gel can be made by add ing amixture of Xanthomonas hydrophilic colloid and locust bean gum to hotwater, and thereafter cooling. The heat reversible, aqueous gel can alsobe made by adding to Water a mixture of Xanthomonas hydrophilic colloidand locust bean gum, and mixing under high shear agitation.

This invention relates to an aqueous heat-reversible gelatinous productand to a method for producing the same. More specifically, the inventionrelates to an aqueous gelatinous product produced by the interaction ofa Xanthomonas hydrophilic colloid with locust bean gum.

Various products such as cranberry sauce, tomato aspic, and the like aresold in the form of an aqueous gel. Prior to consumption, the productsare removed from the cans or containers in which they are sold andplaced in a serving dish which is then placed on the table. In placingthe products on the table, the housewife will, of course, arrange themin an attractive manner such that their appearance is appetizing andcontributes to the overall appearance of the dinner table.

The housewife may frequently desire to serve a gelled product in theform of a decoratively molded article. This can be convenientlyaccomplished, for example, in the case of a gelation salad or dessert bymixing the salad or dessert ingredients in a hot fluid state andthereafter placing them in a suitable mold which is then placed underrefrigeration and cooled to form the salad or dessert.

Although gelled salads or desserts may be conveniently prepared indecorative molds, it is frequently desirable to purchase a material inthe form of a gel which is heat reversible. Thus, even though the gelmay be broken in removing it from the container in which it is supplied,the gel structure can be restored merely by placing the gel pieces in asuitable mold and reheating.

An object of this invention is to provide a novel heat reversibleaqueous gel and a method for its preparation.

A further object of this invention is to provide a novel aqueousgelatinous composition having particular application for use as a salador dessert gel and which can be removed from its original container andremolded to give it a different configuration.

A still further object of this invention is to provide a method forforming aqueous gels such that they are heat reversible.

Additional objects of the invention will appear from a reading of thespecification and claims which follow.

In accord with my invention, I have found that I can accomplish one ormore of the foregoing objectives, and in particular produce a highlydesirable heat reversible aque- 3,557,016 Patented Jan. 19, 1971 ous gelwith the products and method hereinafter described.

In a general sense, my invention involves the addition of a smallquantity of a Xanthomonas hydrophilic colloid in admixture with locusbean gum to hot water. Preferably the temperature of the water rangesfrom about 150 to about 180 F. More preferably, the temperature of theWater is approximately 180 F The limiting factor in Water of asufliciently high temperature is the solubility of the locust bean gumin Water. Locust bean gum is sparingly soluble in water at 70 F and itssolubility increases gradually above this point with increasingtemperature. As stated above, a preferred temperature range for the hotWater is from about 150 F. to about 180 F. The gel forming ingredientsare generally held at this temperature for a time of about 15 minutes.Using higher temperatures, which may be desirable in some instances, thetime may be reduced to a lesser time such as 5 minutes. The time,temperature, and the degree of agitation employed in blending the gelforming ingredients with hot water can all be varied with respect toeach other so long as a suflicient quantity of the locust bean gurn goesinto solution in the hot water.

The total quantity of the Xanthomonas hydrophilic colloid and locustbean gum which I employ is in the range from about 0.02% to about 4% byWeight of the water to which it is added. Preferably, however, the totalquantity of Xanthomonas hydrophilic colloid and locust bean gum is inthe range of about 0.1% to about 1% by weight of the water since I havefound that superb gels are formed at concentrations Within this range.

{The ratios of locust bean gum to Xanthomonas hydrophilic colloid whichI employ can be varied over a wide range. Thus, for example, I havefound that weight ratios of Xanthomonas hydrophilic colloid to locustbean gum from about :5 to about 5:95 produce usable gels. Preferredweight ratios of a Xanthomonas hydrophilic colloid to locust bean gumgenerally range from 75:25 to 40:60.

A convenient means for employing my invention involves the formulationof a gellable composition which, when added to hot water andsubsequently cooled, results in the formation of a gel. The essentialingredients in my invention, namely a Xanthomonas hydrophilic colloidand locust bean gum, are' preferably mixed in dry finely divided form togive a homogeneous mixture such that they are readily soluble in water.Preferably, the particle size of the finely divided locust bean gum andXanthomonas hydrophilic colloid is such that of the ingredients willpass through a 100 mesh screen. To these essential ingredients, theremay, of course, be added various conventional food ingredients such assugar, spices, vegetable coloring materials, and the like. The optionalfood ingredients may be present in any desired concentration dependingupon the taste characteristics desired in the gelled product.

When the optional food ingredients, as outlined above, are co-presentwith a Xanthomonas hydrophilic colloid and locust bean gum in a dry mix,the optional food ingredients are preferably in a finely dividedcomminuted form such that they are readily soluble in water. In thecase, however, Where my invention is employed in the forming of a heatreversible gel, the gel may contain vegetables, fruits, and the likedispersed throughout. This can be readily accomplished, for example, inthe case of a dessert gel by adding a Xanthomonas hydrophilic colloidand locust bean gum to hot Water in the manner described previously andthen adding the fruits, vegetables, etc. after cooling to a temperature,e.g., to R, where the viscosity of the system is sufficiently high tosuspend the solid materials which are added.

Gels which are formed according to my invention are,

3 in general, quite cohesive. In certain use applications, a lesscohesive gel would be desirable. In this event, my gel can be altered byincorporating therein small quantities of additives which would make thegel more plastic. Examples of such additives are guar gum, carboxymethylcellulose, gum karaya, gum tragacanth, alginates, gum arabic, gumcarrageenan, and starches. The quantities of such additives may bevaried, as desired, to reduce the cohesiveness of my gels to whateverdegree is necessary.

The Xanthomonas hydrophilic colloids employed in my invention arecolloidal materials which are produced by bacteria of the genusXanthomonas. Illustrative of such colloidal materials is the hydrophiliccolloid produced by the bacterium Xanthomonas campestris. This colloidalmaterial is a polymer containing mannose, glucose, potassium glucuronateand acetyl radicals. In such a colloid, the potassium portion can bereplaced by several other cations without substantial change in theproperty of the said materials for my purpose. The said colloid, whichis a high molecular weight, exocellular material, may be prepared by thebacterium Xanthomonas campcstris, by whole culture fermentation of amedium containing 25% commercial glucose, organic nitrogen source,dipotassium hydrogen phosphate and appropriate trace elements. Theincubation time is approximately 96 hours at 28 C., aerobic conditions.In preparing the colloid as aforesaid, it is convenient to use cornsteep liquor or distillers dry solubles as an organic nitrogen source.It is expedient to grow the culture in two intermediate stages prior tothe final inoculation in order to encourage vigorous growth of thebacteria. These stages may be carried out in media having a pH of about7. In a first stage a transfer from an agar slant to a dilute glucosebroth may be made and the bacteria cultured for 24 hours under vigorousagitation and aeration at a temperature of about 30 C. The culture soproduced may then be used to inoculate a higher glucose (3%) contentbroth of larger volume in a second intermediate stage. In this stage thereaction may be permitted to continue for 24 hours under the sameconditions as the first stage. The culture so acclimated for use withglucose by the aforementioned first and second stages is then added tothe final glucose medium. In the aforesaid method of preparation ofXanthomonas campestris hydrophilic colloid, a loopful of organism fromthe agar slant is adequate for the first stage comprising 200milliliters of the said glucose media. In the second stage the materialresulting from the first stage may be used together with 9 times itsvolume of a 3% glucose media. In the final stage the material producedin the second stage may be admixed with 19 times its volume of the finalmedia. A good final media may contain 3% glucose, 0.5% distillers drysolubles, 0.5% dipotassium phosphate, 0.1% magnesium sulphate having 7molecules of water of crystallization and water. The reaction in thefinal stage may be satisfactorily carried out for 96 hours at 30 C. withvigorous agitation and aeration. The resulting Xanthomonas campestriscolloidal material which I have found to be particularly suitable for mypurpose can be recovered by precipitation in methanol of the clarifiedmixture from the fermentation. This resulting material may also bedesignated as a pseudoplastic, heteropolysaccharide hydrophilic colloidor gum produced by the bacterium species Xanthomonas campestris.

Other Xanthomonas colloidal materials may be prepared by repeating theprocedure used for producing the Xanthomonas campestris colloidalmaterial described above by substituting known Xanthomonas bacterium ororganisms, i.e., Xanthomonas carotae, Xanthomonas incanae, Xanthomonasbegoniae, and Xanthomonas malvacearum, for the bacterium, Xanthomonascampeslris.

To illustrate the wide variety of gels which may be formed according tomy invention, a series of tests were performed. In these tests, aXanthomonas hydrophilic colloid, prepared as described previously andlocust bean gum, with both the Xanthomonas hydrophilic colloid andlocust bean gum being present in finely divided form, were dry blendedand added to distilled water having a temperature of 180 F. The totalconcentration of Xanthomonas hydrophilic colloid and locust bean gum was1% by weight of the aqueous component. After being held at 180 F. for 15minutes with constant agitation, each of the various mixtures was pouredinto Bloom Gelometer bottles and allowed to stand for 17 hours at roomtemperature. Each of the various samples was then checked to determineits Bloom gel strength. The results of these tests are set forth in thefollowing table in which the first column describes the percentconcentration of Xanthomonas campcstris hydrophilic colloid based on theweight of the aqueous medium, the second column describes the percentconcentration of locust bean gum based on the weight of the aqueousmedium, and the third column describes the Bloom Gelometer reading foreach of the samples in grams.

TABLE I Percent of Xanllto- Percent of Bloom golommonas campat'trz'shydrolocust bean cter reading philic colloid gum in grams 0.95 0. 15. 10..)0 0. 21. 4 0.85. 0. 26. 4 0.80. 0. 20 31. 5 0.75. 0. 42. 3 0.70 0.40. 3 0.65 a a. 0.35 30. 6 0.60 0. -10 42. 2 0.50 0. 41. 0 0. 10 0. 40.0 0.35 0. 34. 6 0.30 0. 27). 9 0.25 0. 25. G 0.20- 0. 23. 0 0.15 0. 18.3 0.10. 0. 15.3 0.05 0.

As shown in the above table, gels were formed over a wide range ofratios of Xanthomonas campestris hydrophilic colloid to locust bean gum.The maximum gel strength was found to occur at weight ratios ofXanthomonas campestris hydrophilic colloid to locust bean gum rangingfrom about 75:25 to about 40:60.

The Bloom Gelometer is an instrument that is available commercially fromthe Precision Scientific Company, 3737 West Cortland Street, Chicago 47,111. It was developed by -Dr. Oscar Bloom of Swift & Company and is usedto determine the gel strength of food products such as gelatin dessertsand starch dessert powders. The instrument is used by governments andinstitutions in testing not only gelatin desserts but other type geldesserts as well. In general, the instrument is a device that contains aone inch diameter Lucite plunger that is lowered a predetermineddistance, usually 4 mm., into the sample. Force applied to the plungerto drive it against the resistance of the gel or jelly is a directmeasure of the gel strength or jelly strength of the material tested.The result is reported in grams.

To further illustrate my invention, additional tests were performed inwhich a Xanthomonas campestris hydrophilic colloid and locust bean gumin finely divided form were dry blended and added to distilled water ata temperature of about F. The total concentration of Xanthomonascampestris hydrophilic colloid and locust bean gum was 1% by weight ofthe aqueous medium with 60 parts of Xanthomonas campestris hydrophiliccolloid being employed for each 40 parts of locust bean gum. After beingadded to water at 180 F., the mixture was agitated for about 15 minuteswhile holding the temperature constant at 180 F. Then the temperaturewas allowed to drop slowly with viscosity measurements being taken witha Brookfield Viscometer, Model LVF, employing a No. 3 or No. 4 spindlerotating at 60 r.p.m. The results of these tests are shown in thefollowing table in which the first column shows the temperature of themixture in degrees Fahrenheit and the second column shows the viscosityof the material in centipoises.

As shown in the above table, a gel is formed at a temperature ofapproximately 118 F. at which point the viscosity rises rapidly. It hasbeen found that the temperature of gel formation can vary slightlywithin the range of about 115 F. to about 125 F. with the transformationtemperature being relatively independent of the exact gel composition.On reheating the gel to the transformation temperature, it has beenfound that the gel is transformed to a liquid at approximately the sametemperature at which the liquid is originally transformed into a gel.

In still a further series of tests, a variety of temperature reversiblegels were formed using various Xanthomonas hydrophilic colloids inadmixture with locust bean gum. The procedure generally employed was todry blend the particular Xanthomonas colloid with locust bean gum witheach being in finely divided form. The dry blended mixture was thenadded to hot water at a temperature of 180 F. to form a mixture whichwas stirred for 15 minutes while maintaining the temperature at 180 F.The hot solution was then poured into a Bloom Gelometer bottle andallowed to stand for 17 hours at room temperature. Following this,gelometer readings were taken for each of the various gels by employinga 1-inch diameter Lucite plunger. The Gelometer was adjustedfor a 4 mm.depression and to deliver 200:5 gms. of shot in 5 seconds. The resultsare set forth in the following table in which column one discloses thepercent concentration of both the Xanthomonas hydrophilic colloid andthe locust bean gum in terms of the weight of the aqueous medium andcolumn two shows the Bloom Gelometer reading obtained for each of thegels. The Bloom Gelometer readings shown in column two are averagefigures based on three separate Bloom Gelometer readings for each of thegels.

TABLE III Percent of Xanthomonas hydrophilic colloid and percent oflocust bean gum: Gms.

0.50% Xanthomonas campestris, 0.50% locust bean gum 40.3 0.625%Xanthomonas malvacearum, 0.50% locust bean gum 77.9 0.875% Xanthomonascarotae, 0.50% locust bean gum 52.6 0.825% Xanthomonas begoniae (St. 3),0.50%

locust bean gum 56.6 0.55% Xanthomonas begoniae (St. 9), 0.50%

locust bean gum 47.4 0.75% Xanthomonas incanae, 0.50% locust bean gum37.0 1.875% Xanthomonas phasebli, 0.50% locust bean gum 44.5 1.00%Xanthomonas campestris, 0.00% locust bean gum 12.7 1.00% locust beangum, 0.00% Xanthomonas campestris 10.0

Bloom Gelometer readings.

As shown in the above table, all of the various Xanthomonas hydrophiliccolloids produced firm, cohesive and thermally reversible gels.Moreover, the table shows that the gel formed from a 50:50 mixtureXanthomonas campestris hydrophilic colloid with locust bean gum had agel strength which was synergistically increased over the gel strengthsproduced by employing either Xanthomonas campeszris hydrophilic coilloidor locust bean gum alone. Specifically, 1% by weight of Xanthomonascampestris hydrophilic colloid produced a Bloom Gelometer reading ofonly 12.7 gms. and 1% by weight of locust bean gum produced a BloomGelometer reading of only 10.0 gms. Yet, unexpectedly, 0.50% ofXanthomonas campestris hydrophilic colloid in admixture with 0.5% oflocust bean gum produced a firm, cohesive gel having a Bloom Gelometerreading of 40.3 gms. Similarly, it has been found that the Xanthomonashydrophilic colloids other than that produced by the bacteriumXanthomonas campestris react synergistically with locust bean gum toproduce firm, cohesive gels whose gel strengths are far in excess ofthat predicted from the individual actions of a Xanthomonas hydrophiliccolloid and locust bean gum.

To further illustrate my invention there are presented the followingexamples in which all parts and percentages are by weight unlessotherwise indicated.

EXAMPLE I A tomato aspic was prepared by dry blending 0.65 part ofXanthomonas campestris hydrophilic colloid, 0.35 part of locust beangum, 1 part of sugar, and 0.70 part of salt. After being dry blended toinsure homogeniety, the finely divided mixture was added to 97.3 partsof tomato juice. The mixture was then heated to F. and subjected toagitation. After holding at 180 F. for approximately 15 minutes, themixture was poured into containers and allowed to cool. There resulted afirm, cohesive and heat reversible tomato aspic gel.

Various fiavor modifiers may be incorporated in the tomato aspicillustrated in Example I. Illustrative of such modifiers are celery,spices, lemon juice, etc. These modifiers are conveniently added to thetomato juice along with the finely divided Xanthomonas hydrophiliccolloid, locust bean gum, sugar, and salt after which the mixture isheated to 180 F. and cooled to give a firm tomato aspic gel.

EXAMPLE II A dietetic jelly was prepared by dry blending 1.00 part ofXanthomonas campestris hydrophilic colloid, 1.00 part of locust beangum, 1.50 parts of calcium cyclamate, 0.10 part of calcium saccharin and0.45 part of sodium benzoate. After the dry blending operation, themixture was added to 450 parts of unsweetened Concord grape juice andthen heated to 180 F. with agitation. After holding at 180 F. forapproximately 15 minutes, the mixture was poured into containers andallowed to cool. There resulted a tender, smooth, and heat reversibledietetic grape jelly.

EXAMPLE III To 40 parts of water was added a dry blended mixturecomprising 0.25 part of Xanthomonas campestris hydrophilic colloid and0.25 part of locust bean gum. After addition to water, the temperatureof the system was raised to approximately 180 F. with agitation. Themixture was then combined with 250 parts of sugar and 250 parts of 4:1(4 parts of strawberries to 1 part of sugar) pack strawberries which hadpreviously been preheated to 180 F. The resulting mixture was thencooked to a temperature of about 220 F. which yielded a soluble solidcontent of approximately 64% by weight. Two parts of citric acid werethen added and dissolved therein. The mixture was then poured intocontainers and allowed to cool. On cooling, there resulted a heatreversible strawberry jam of excellent quality.

7 EXAMPLE IV To 201 parts of water were added 0.25 part of Xanthomonascampestris hydrophilic colloid and 0.25 part of locust bean gum, both infinely divided form. After dissolving these materials in the water, 2.01parts of a surface active agent were added. Illustrative of suitablesurface active agents are the materials which are sold commercially asPluronic L-44 by Wyandotte Chemical Co. Typical of such surface activeagents are the anionic and nonionic materials including, for example,oleic acid amides, alcohol sulfates, alkyl aryl ethers, alkyl arylsulfonates, and the like. There are then added 0.39 part of sodiumorthophenyl phenate (a suitable material for this purpose is offeredcommercially by Dow Chemical Co. as Dowicide A), 12.3 parts ofglycerine, 30.15 parts of a finely divided diatomaceous earth. Afterthese materials are added, the mixture was mixed to insure homogeneityand heated to 140 F. where 47.6 parts of a light mineral oil and 4.2parts of carnauba wax were added. The temperature was then raisedfurther to 175 F. with stirring until the wax was dissolved in thesystem. The material was then passed through a colloid mill orhomogenizer and poured into containers and allowed to cool. Thereresults an excellent cleaner and polish for auto enamels which exists inthe form of a soft gel having excellent suspending and emulsionstability properties.

As set forth previously, the aqueous heat reversible gels producedaccording to my invention are preferably produced by adding thenecessary ingredients, i.e., a Xanthomonas hydrophilic colloid andlocust bean gum, to hot water whereupon the gel forms on cooling of themixture to a temperature below about 125 F. Also, however, the gelswhich are the subject of m invention can be produced through a coldprocess in which locust bean gum and a Xanthomonas hydrophilic colloidare added to a cold aqueous system which is then subjected to vigorousagitation and allowed to set. In producing gels through use of a coldprocess, I generally employ from about 0.10% to about 2% by weight(total) of the Xanthomonas hydrophilic colloid and locust bean gum basedon the weight of the aqueous component and, preferably I employ a totalconcentration in the range of about 0.2% to about 1%.

Gels formed according to my cold process are obtained almostinstantaneously under the influence of high shear agitation. It has beenfound that the gel strength increases to some degree on aging or onfurther cooling of the gel. Aging or additional cooling is, however, notcritical to forming a cold gel according to my invention.

To further illustrate this aspect of my invention there is presented thefollowing example.

EXAMPLE V To 183 parts of water were added 1.75 parts of Xanthomonascampestris hydrophilic colloid, and 1.75 parts of locust bean gum. Themixture was agitated at high shear in a Waring Blendor for 30 seconds.There was then added 4 parts of a surface active agent, as definedpreviously, such as the product which is sold commercially as Regal H Dby Armour and Co., and mixing was continued at a lower speed to minimizefoaming. Ten parts of trisodium phosphate were then added and mixing wascontinued until the trisodium phosphate had dissolved. There resulted anoven cleaner composition which had a high viscosity and asemi-gelatinous body. It was found that the composition could be easilyapplied to oven surfaces and exhibited excellent cling even on verticalsurfaces. Further, the gelled structure of the oven cleaner wasreversible under the influence of temperature which proved advantageous.To illustrate, after treating the oven surfaces with the cleanercomposition, it was not necessary to remove the cleaner in the usuallaborious manner along with the dissolved or loosened grease and charreddebris. Rather, removal of the oven cleaner was accomplished by simplywarming the oven to a temperature of about 150 F. at which temperaturethe viscosity of the oven cleaner had decreased to the point where amajor portion of it drained to the bottom of the oven such that it couldbe easily removed.

A still further aspect of my invention arises from the discovery that aXanthomonas hydrophilic colloid and locust bean gum, when presenttogether in an aqueous system, produce a synergistic increase in theviscosity of the aqueous system. When utilizing a mixture of aXanthomonas hydrophilic colloid with locust bean gum in order to producea synergistic viscosity increase in an aqueous system, I have found thata synergistic effect is obtained using varying ratios of Xanthomonashydrophilic colloid to locust bean gum ranging from about 95:5 to about5:95. A preferred ratio of Xanthomonas hydrophilic colloid to locustbean gum ranges from :20 to 20:80 since the synergistic viscosityincrease produced within this range is greater than at ratios outsidethis range. A most preferred ratio comprises about 40 parts by weight ofa Xanthomonas hydrophilic colloid for each 60 parts of locust bean gumsince the greatest viscosity increase has been observed at weight ratiosof this order.

When utilizing a mixture of a Xanthomonas hydrophilic colloid withlocust bean gum for the purpose of either producing a cold gel orsynergistically increasing the viscosity of an aqueous system, I employa total concentration of the Xanthomonas hydrophilic colloid and locustbean gum ranging from about 0.10%to about 2% by weight of the aqueouscomponent. Amounts in the range of 0.2% to about 1% by weight of theaqueous component are preferred.

To illustrate the wide range of ratios over which a Xanthomonashydrophilic colloid and locust bean gum give a synergistic increase inviscosity, a number of aqueous solutions were formulated which containedvarying ratios of a Xanthomonas hydrophilic colloid and locust bean gum.The Xanthomonas hydrophilic colloid employed in these tests was formedby the bacterium Xanthomonas campestris according to the methoddescribed previously with the colloid being separated by drying theclarified mixture resulting from the final fermentation step using adrum dryer which was heated .with steam at 40 p.s.i. The dried colloidalmaterial was removed from the surface of the drum with a sharp knife.

or doctor blade.

In Table IV which follows, the total content of the Xanthomonascampestris hydrophilic colloid and locust bean gum employed in each testrun was 1% by weight of the total solution. The materials were dryblended and then added to distilled water and stirred for 15 minuteswith a disc type stirrer rotating at 900 rpm. The disc stirrer compriseda 1% in. diameter disc divided into four radial lobes. The lobes werebent from the plane of the disc such that the leading edges of each ofthe lobes were approximately in. below the plane of the disc and thetrailing edges of each of the lobes were approximately Vs in. above theplane of the disc. Following the stirring, the viscosity was immediatelyrecorded with a Brookfield Viscometer, Model LVF, using a spindlerotating at 60 rpm.

As shown in Table IV, a wide range of mixtures of a Xanthomonashydrophilic colloid with locust bean gum gave a synergistic increase inviscosity. A synergistic increase in viscosity was obtained at weightratios ranging from 95 parts of a Xanthomonas hydrophilic colloid with 5parts of locust bean gum to 5 parts fa Xanthomonas hydrophilic colloidwith 95 parts of locust bean gum. The greatest viscosity increase wasobserved at weight ratios of about 80:20 to about 20:80, and the optimumviscosity increase was observed using approximately 60 parts of locustbean gum for each 40 parts of a Xanthomonas hydrophilc collod.

The test series set forth in Table IV was repeated using the sameingredients and weight ratios and employing higher shear agitation. Inthis instance, the dry blended materials were added to distilled waterwhich was mixed in a Waring Blendor at high speed for 2 minutes. Theresults are shown in Table V.

As shown in Table V, the viscosity increase obtained is dependent uponthe amount of shear employed in the agitation. It should be noted,however, that the greatest viscosity improvement occurred at weightratios of 80:20 to 20:80 as observed in Table IV and that the optimumviscosity improvement was observed at a weight ratio of approximately 60parts of locust bean gum to 40 parts of a Xanthomonas hydrophiliccolloid.

To demonstrate the synergistic viscosity increase ob tained throughmixing locust bean gum with a Xanthomonas hydrophilic colloid, a furtherseries of tests were carried out. In these tests, a wide variety ofXanthomonas hydrophilic colloids were separately added to water andagitated at high shear in a Waring Blendor for 30 seconds. The viscositydeterminations were then immediately made by a Brookfield Viscometer,Model LVF, using a spindle speed of 30 rpm. The particle size of theXanthomonas hydrophilic colloids employed and the locust bean gum weresuch that 100% of the material passed through a l00-mesh screen. Theresults of these tests are set forth in the following Table VI.

TABLE VI Concentration Viscosity Concentration of Xanthomonas oi locustbean of solution hydrophilic colloid gum (percent) (c.p.s.)

1.0% Xanthomonas campestris 1. 0 gg 0.5% Xanthomonas campestris 0. 2,8001.0% Xanthomonas malvaceamm XM13 1, 280 0.5% Xanthomonas malvacearumXM13 0. 5 3.800 1.0% Xanthomonas malvacearum R2- 1, 760 0.5% Xanthomonasmalvaceamm R2 0. 5 6, 400 1.0% Xantohmonas begzmiae S9 1, 560 0.5%Xanthomonas begom'ae $9.... 0. 5 5, 600 1.0% Xanthomonas begom'ae S3 50005.% Xanthomonas begomae S3-.. 0. 5 3,800 1.0 Xanthomonas phaseoli 200.5 o Xanthomonas phaseoli 0. 5 2, 000 1.0% Xanthomonas carutae XCII1,000 0.5% Xanthomonas carotae X01 0. 5 4, 000 1.0% Xanthomonas inczmae1, 800 0.5% Xanthomonas incanae 0 5 7,000

As shown in Table VI, a wide variety of Xanthomonas hydrophilic colloidswere found to produce a synergistic increase in the viscosity of anaqueous solution when added thereto in admixture with locust bean gum.The various Xanthomonas hydrophilic colloids indicated in the table wereproduced in the manner set forth previously for a Xanthomonas campestrishydrophilic colloid with the exception that a different strain ofbacterium was employed in the process, the strain of bacterium beingindicated in Table VI.

in practicing my invention, I sometimes prefer to employ a Xanthomonashydrophilic colloid which is prepared by a slightly different methodthan that set forth previously. This is particularly true in theformation of a gel according to my cold process or in the formation of asynergistically thickened aqueous system through the addition of aXanthomonas hydrophilic colloid and locust bean gum thereto. In thealternative method for preparing Xanthomonas hydrophilic colloid, thecolloidal material is not recovered by precipitation as, for example, inmethanol. Rather, the clarified mix resulting from the finalfermentation step of the process is dried by the application of heat. Toillustrate, the hydrophilic colloidal material can be separated bypassing the clarified mixture from the fermentation to a drum dryerwhich is heated with steam at 40 p.s.i. The dried film on the drumsurface can thereafter be removed with a sharp knife or doctor blade.Alternative drying methods may also be employed in separating thehydrophilic colloidal material. Thus, for example, the hydrophiliccolloidal material may be separated by subjecting the clarified mix turefrom the fermentation to spray drying, etc.

The water temperature employed in forming a gel according to a coldprocess or in forming a synergistically thickened aqueous systemaccording to my invention is not critical. Thus, for example, cold gelscan be formed with water of various temperatures such as 45 F. or 75 F.and synergistically thickened aqueous systems can likewise be formedusing water of such varying temperatures.

Having fully defined my invention in the foregoing specification, Idesire to be limited only by the lawful scope of the appended claims.

I claim:

1. A composition for thickening an aqueous medium or forming a heatreversible, aqueous gel, said composition comprising a Xanthomonashydrophilic colloid and locust bean gum, wherein the weight ratio ofsaid Xanthomonas hydrophilic colloid to said locust bean gum ranges fromabout :5 to about 5:95.

2. The composition of claim 1 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium Xanthomonas campestris.

3. The composition of claim 1 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium Xanthomonas malvacearum.

4. The composition of claim 1 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium Xanthomonas carotae.

5. The composition of claim 1 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium Xanthomonas begoniae.

6. The composition of claim 1 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium Xanthomonas incanae.

7. The composition of claim 1 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium Xanthomonas phaseoli.

8. The composition of claim 1 wherein said Xanthomonas hydrophiliccolloid and said locust bean gum are finely divided such that of theingredients will pass through a l00-mesh screen.

9. A composition for thickening an aqueous medium or forming a heatreversible, aqueous gel, said composition comprising a Xanthomonashydrophilic colloid in admixture with locust bean gum, the weight ratioof said Xanthomonas hydrophilic colloid to said locust bean gum rangingbetween about 80:20 to about 20:80.

10. The composition of claim 9 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium X anthomonas cam pestris and theweight ratio between said Xanthomonas campestris hydrophilic colloid andsaid locust bean gum is approximately 40:60.

11. A process comprising adding a mixture of a Xanthomonas hydrophiliccolloid and locust bean gum to hot water which is then cooled to form aheat reversible gel, the total quantity of said Xanthomonas hydrophiliccolloid and said locust bean gum ranging from about 0.02% to about 4% byWeight of the hot water, and the Weight ratio of said Xanthomonashydrophilic colloid to said locust bean gum ranging from about 95:5 toabout 5:95.

12. The process of claim 11 wherein said Xanthomonas hydrophilic colloidis produced by the bacterium Xanthomonas campestris.

13. The process of claim 11 wherein said Xanthomonas hydrophilic colloidis produced by the bacterium Xanthomonas malvacearum.

14. The process of claim 11 wherein said Xanthomonas hydrophilic colloidis produced by the bacterium Xanthomonas camtae.

15. A process for preparing a viscous aqueous medium by reacting locustbean gum and a Xanthomonas hydrophilic colloid in said medium,comprising adding locust bean gum and a Xanthomonas hydrophilic coloidto water, wherein said Xanthomonas hydrophilic colloid and said locustbean gum are employed at a total concentration ranging from about 0.10%to about 2.0% by weight of the aqueous medium, and the weight ratio ofsaid Xanthomonas hydrophilic colloid to said locust bean gum ranges fromabout 95 :5 to about 5:95.

16. The process of claim 15 wherein said Xanthomonas hydrophilic colloidis produced by the bacterium Xanthomonas campestris.

17. A viscous aqueous medium comprising water containing a mixture of aXanthomonas hydrophilic colloid and locust bean gum, wherein said locustbean gum and Xanthomonas hydrophilic colloid are present at a totalconcentration ranging from about 0.10% to about 2% of the aqueousmedium, and the weight ratio of said Xanthomonas hydrophilic colloid tosaid locust bean gum ranges from about 95:5 to about 5:95.

18. The composition of claim 17 wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium Xanthomonas campestris.

19. The composition of claim 17, wherein said Xanthomonas hydrophiliccolloid is produced by the bacterium X anthomonas begoniae.

20. A process for preparing a heat reversible aqueous gel, said processcomprising adding to water a Xanthomonas hydrophilic colloid and locustbean gum and References Cited UNITED STATES PATENTS 2,466,146 4/1949Baker 252316X 2,639,268 5/1953 Heiss 2523l6X 2,927,055 3/1960 Lanzet252316X 3,020,206 2/196'2 Patton et al. 1953l OTHER REFERENCES NewPolysaccharide Gums Produced by Microbial Synthesis, ManufacturingChemist, vol. 31, May, 1960, pp. 206208.

RICHARD D. LOVERING, Primary Examiner US. Cl. X.R.

' UNITED STATES IA'JEN'I OFFICE CER'IIFICA'IE OF CORRECTION Patent No.3,557,016- Dated January 19, 1971 Inventor) HARRY R SCHUPPNER, JR.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

I In line 47, column 1, the word elation" should read 9 --gelac.1n--.

In line 5, column 2, the word appearing as "locus" shou read locust--.

In Table VI, the bracket "j( should be deleted and the number "1. 0"appearing next to the bracket should be moved doz-m one line to the sameline as the number "20" in the la column. with this change the upperportion of Table VI wi read as follows:

. TABLE VI CONCENTRATION OF XAN'ifIlOF-IONAS CONCENTRATION OF VISCOSITHYDROPHILIC COLLOID LOCUS'I BEAN GUM SOLUTION (Percent) (c.p.s.

1.0% Xanthomonas campestris 1,800

Signed and sealed this 1 0th day of August I 971 (SEAL) Attest:

EDWARD M. FLETCHERJR. WILLIAM E. SCHUYLER, J L Attesting OfficerCommissioner of Patent

